Calcium sensing receptor forms complex with and is up-regulated by caveolin-1 in cultured human osteosarcoma (Saos-2) cells
Experimental & Molecular Medicine
;
: 91-100, 2005.
Article
in English
| WPRIM
| ID: wpr-90143
ABSTRACT
The calcium sensing receptor (CaSR) plays an important role for sensing local changes in the extracellular calcium concentration ([Ca2+]o) in bone remodeling. Although the function of CaSR is known, the regulatory mechanism of CaSR remains controversial. We report here the regulatory effect of caveolin on CaSR function as a process of CaSR regulation by using the human osteosarcoma cell line (Saos-2). The intracellular calcium concentration ([Ca2+]i) was increased by an increment of [Ca2+]o. This [Ca2+]i increment was inhibited by the pretreatment with NPS 2390, an antagonist of CaSR. RT-PCR and Western blot analysis of Saos-2 cells revealed the presence of CaSR, caveolin (Cav)-1 and -2 in both mRNA and protein expressions, but there was no expression of Cav-3 mRNA and protein in the cells. In the isolated caveolae-rich membrane fraction from Saos-2 cells, the CaSR, Cav-1 and Cav-2 proteins were localized in same fractions (fraction number 4 and 5). The immuno-precipitation experiment using the respective antibodies showed complex formation between the CaSR and Cav-1, but no complex formation of CaSR and Cav-2. Confocal microscopy also supported the co-localization of CaSR and Cav-1 at the plasma membrane. Functionally, the [Ca2+]o- induced [Ca2+]i increment was attenuated by the introduction of Cav-1 antisense oligodeoxynucleotide (ODN). From these results, in Saos-2 cells, the function of CaSR might be regulated by binding with Cav-1. Considering the decrement of CaSR activity by antisense ODN, Cav-1 up-regulates the function of CaSR under normal physiological conditions, and it may play an important role in the diverse pathophysiological processes of bone remodeling or in the CaSR- related disorders in the body.
Full text:
Available
Index:
WPRIM (Western Pacific)
Main subject:
Bone Neoplasms
/
Osteosarcoma
/
Up-Regulation
/
Cell Fractionation
/
Cell Membrane
/
Calcium
/
Microscopy, Confocal
/
Oligoribonucleotides, Antisense
/
Caveolins
/
Cell Line, Tumor
Limits:
Humans
Language:
English
Journal:
Experimental & Molecular Medicine
Year:
2005
Type:
Article
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